Without loss of generality, given virtual network request [G.sup.V] = ([N.sup.V], [E.sup.V]), and substrate network [G.sup.S] = ([N.sup.S],[E.sup.S]), the SVNE against single substrate node failure (SVNE-N) problem is to map the virtual network to the substrate network to accept maximum VNs with minimum resources while satisfying the follows: (i) for each virtual node/link, it is mapped to the substrate network meeting the capacity/bandwidth/location constraint; (ii) the important virtual node is protected against any single substrate node failure.
In this section, a SVNE scheme based on load balancing and reconfiguration is proposed to survive the VNs from single substrate link failure with high resource efficiency.
As we know, in SVNE problem, substrate resources could be provisioned as primary resources or backup resources.
This idea, to our best knowledge, is used in the SVNE problem for the first time.
We setup the simulation and choose the parameters in accordance with the previous works on SVNE or VNE problem   .
In SVNE embedding case, there will be extra cost of backup resources.
The compared approaches for SVNE against link failure are illustrated in Table 1.
The compared approaches for SVNE against node failure are illustrated in Table 2.
In this paper, we dwell on the SVNE against such failure scenarios separately from the perspective of improving the resource efficiency.
This idea is applied in our heuristic algorithm to solve the SVNE against substrate link failure in this paper.
In the future, we plan to extend the proposed methods to solve SVNE problem in more complex failure scenarios, such as multiple substrate failures, and regional failure.
 Rahman M, Aib I and Boutaba R, "SVNE: Survivable Virtual Network Embedding Algorithms for Network Visualization," IEEE Transactions on Network and Service Management (TNSM), vol.